Suggest Treatment For Pain

hi i have a really bad cramping/spasim pains in the left hand side of my stomach and i have to been to the doctors continuasily and they think its ibs but they just give me tablets and there not working. i have had a ultra scan and blood tests but they cant seem to fing out what it is i have had to take time of work beacuse my job is standing up, and thats when the pain starts its fine when i am sitting but gets painfull when standing a walking its making me depressed can you help me?